The temperature probe of the invention is primarily although not exclusively intended for use in clinical laboratories for measuring temperatures of serum and reagents in cuvettes. Such cuvettes typically contain 30-1000 microliters of serum and reagent. One objective of the invention is to provide a temperature probe which is constructed to minimize temperature changes in the cuvette as the probe is making its temperature measurements.
The foregoing temperature measurements may be made in two ways. For example, the probe may be inserted into the aqueous solution in a cuvette and a reading made as soon as the indication settles. This typically occurs, for example, within 10 seconds Alternately, the probe may be inserted into a cuvette and left in the aqueous solution in the cuvette for an extended time interval before a measurement is taken.
In the first case it is important that the heat capacity of the probe be minimal, and it is also important that the probe have a fast response time. In the second case it is important that the heat transfer out of the aqueous solution in the cuvette by the probe be minimal. The probe of the present invention is particularly constructed to meet all of the criteria set forth above.
Accordingly, the objectives of the present invention are to provide an inexpensive rugged thermistor-type liquid temperature probe which has long term stability, and which includes a thermistor of low thermal capacity, and which also includes insulated thermistor lead wires of low thermal conductivity.
It is a further objective of the invention to provide such a probe which has low heat dissipation, and which exhibits a high output signal level when connected to a measuring circuit.
In the construction of the probe of the invention, the thermistor itself is electrically isolated from the aqueous solution whose temperature is being measured so that shunt leakage current across the thermistor may be negligible.